
i.e., the areal radius \(C\)  and the collapsing velocity \(\mathbb {U}\) 
are proportional to one another. In Newtonian
hydrodynamics
[1]}, [2]}, [3]}
the homologous evolution is characterized by this expression.
Therefore, for two concentric spherical shells of radii say
\(C_{1}\)  and \(C_{2}\) , assigned by \(r=\mathfrak {r}_{2}\) =constant, and
\(r=\mathfrak {r}_{1}\) =constant, respectively, we get
\(\frac{C_{1}}{C_{2}}=\textmd {constant}.\) 
